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zinc-base alloys containing mainly aluminum, copper, or magnesium (see Table 1). Zinc alloys are characterized by a low melting point and good flowability; they are readily worked by pressure and cutting and are easily welded and soldered. Metallic and nonmetallic coatings can be deposited by electrochemical and chemical methods on products made of zinc alloys. The corrosion resistance of the alloys is about the same as that of commercial zinc and galvanized steel. The disadvantages of zinc alloys are their poor mechanical properties at elevated temperatures (particularly resistance to creep), the tendency to alter dimensions in the course of natural aging, and the poor corrosion resistance in corrosive acidic and alkaline media.
|Table 1. Chemical composition and uses of zinc alloys|
|Composition1 (percent by weight)||Uses|
|1The rest is zinc|
|3.5–4.3||—||0.02–0.06||For products cast under pressure|
|—||0.8–1.2||0.01||For products obtained by rolling, stamping, and deep drawing|
|22||Upto 1||Upto 0.1||For products of complicated shape obtained by pneumatic forming in a superplastic state|
The most common zinc alloys are those used in pressure die casting to produce structural and decorative components of motor vehicles, electrical machines, office machinery, household appliances, souvenirs, and other objects. Compared with other alloys used in pressure die casting, zinc alloys are more practical and permit thin-walled castings to be obtained. They are used as antifriction materials in bearing linings (cast, compressed, and bimetallic types); they are good alternatives for the tin-bronzes and the low-tin Babbitt metals.
Zinc alloys that are worked under pressure in the form of rolled sheets are used in various branches of technology for the manufacture of products by deep stamping or pneumatic forming in a superplastic state; they are also used in the printing industry (zincography). Stamping and forming dies for aluminum alloys are produced from thick rolled plates. Rolled semifinished products made from zinc alloys exhibit pronounced anisotropic properties.
REFERENCESpravochnik po mashinostroitel’nym materialam, vol. 2: Tsvetnye metally i ikh splavy. Moscow, 1959.
I. L. ROGEL’BERG